Grinding system for ore, rock, etc.



Nov'. 24, A19215.

H. K. BURCH GRINDING SYSTEM FOR. ORE, ROCK, ETC

Filed Apri/1 1. 192.4

2 Sheets-Sheet 1- Afro/hy H. K. BURCH GRINDING SYSTEM FOR ORE, ROCK, ETC

Filed April 1r 1924 z sheets-sheet '2 A INIENTOR. y/fC ATTORNEY.

vfull rate of eiiiciency and Patented Nov. 24, 1925.

UNITED STATES y l v156.2,618 PATENT OFFICE.

HENRYKENYN BURCH, OF LOS ANGELES, CALIFORNIA.

GRINDING SYSTEM FOR ORE, ROCK, ETC:

Application mea April 1, 192i. serial No. 703,341.

particularly to' a -system or apparatus, for

this purpose comprising grinding mills such as tubular or conical mills using balls or rods as grinding media and adapted to subject the ore or rock to successive grinding operations for progressive reduction in size of such material. My invention is further adapted for application in a systemV of this kind wherein a classifier is connected to the outlet of each mill aforesaid toreceive the ground product from such mill and separate the finely ground material from the coarser material. In practice it has been customary to pass the coarser material from the classi'- fier for the first mill to. a secondary Orindiiig mill wherein it is further reduced to a state of finer division. I havefound that with such an arrangement of mills or classifiers operating under normal conditions, when the coarser material from the classifier for the coarse grinding mill is all passed to the fine grinding mill, the -full efficiency of the coarse grinding mills is not obtained, there being a tendency under such condiltions for the vcoarse grinding mill to be underfed and to operate with less than its capacity.

An important object of the presentk inventioii is to overcome the above stated disadvantage and to provide for full working eliiciency and capacity of bothY the coarse ii grinding and line grinding mill. This object I attain by providing for returning to the coarse grinding mill of a certain amount of the coarse material separated by the classifier for said mill so as to always maintain a total feed for the coarse grinding mill sufficient to provide for most elfective operation thereof.

The accompanying drawings illustrate an embodiment of my invention and referring thereto, Fig. 1 'is aY diagrammatic plan View of two grinding mills with associated classi-- ers and -with the necessary connections for carryino out my invention 1n connection therewith. Fig. 2 isa plan viewl of the splitting Vmeans for returning a portion of the coarse material from the lirst classifier to the first grinding mill. Fig. 3 is a section on line 8-3 in Fig. 2. Figs. 4 and 5 are a plan view and a vertical' section respectively of a form of classifier suitable for use in connection with my invention.

The apparatus shown in Fig. 1 comprises a coarse grindingmill indicated at 1 which may be of any suitable construction for example a tube or conical mill using balls, rods, or other grinding media, a classifier 2 connected to receive the product from mill l,

a second or fine grinding mill 3, a classier v 4 associated therewith and suitable connections as hereinafter described. -Mill 1 is provided with feed means 5` of any suitable kind for supplying thereto the material to be ground and with delivery means 6 for conducting the ground material from the mill 1 to theclassifier 2. classifiers 2 and 4 may be screens or other classifying means,

for example they may be of the usual type of Dorr classifier, as shown for example, on page 1343, Vol. III of Ore Dressing- Richards, 1909, first edition, in which the material is supplied into a body or current of water and the coarse material is raked or rawn from said body or current of water onto an inclined table` by automatically operated vraking means and the line material is discharged with the water to an outlet 7. An elevator indicated at 8may be provided for delivering the coarse ground product from means. 6 to the classilier type of Dorr classifier well-known in the art kwhich may be used in this connection is shown in Figs. 4 and 5, it being understood however that this type of classifier is shown for illustration purposes only. Said classier comprises an inclined bed or table 18 provided with side members 19 and an end member 2O at the lower end thereof so as to provide a liquid receptacle'at thelowerportion of the table 18. Said end member 2O may befprovided with liquid overflow means 2l. `lAlaiinder 22 maybe provided extending above said liquid receptacle and between the side members 19 so as to receive the material delivered between elevating means 8 2. A standard above referred to and provided with suitable f openings indicated at 23 for distributing or feeding such material into the body of liquid on the table. A. plurality'of transversely extending rakes 24 'are mounted on suitable longitudinal frame means 25, and suitable means are provided for intermittently raising and lowering said rakes and for moving the same upwardly over the table l13 while ed at 34 and provided with arms-31 and 32 connected for operation of the lifting means 26 and 2T respectively. Said cam member QS may be mounted on shaft33 which may be driven in any suitable manner for example by means of gear wheel 35 thereon, pinion 36 and drive pulley 3T. The longitudinal movement of the ralie means may be effected by means of connecting rods v38 connected to crank 39 on shaft 33 and to a cross-head 40 secured to said raking means. As shown in Fig. 4 two sets of rakes 24 are generally provided at the respective sides of the table, each of said sets being independently mounted on frame means :25 and being provided with separate lifting means and means for longitudinal movement as above described. Upon rotation of shaft 33 cam means Q8 will cause lifting means 26 and 27 to be alternately raised and lowered and connecting rod 38 will be operated in synehronism therewith so as to move the rake means upwardly along the table while they are in lowered position and to move the same downwardly toward the;lower end of the table while they are in raised-position. The two sets of raking means are preferably operated alternately so that one is being raised while the other is lowered. In this manner the'coarse material settling to the bottom of the table. from the body of liquid 4 .thereon is continually raked up along the table and discharged at the upper end thereof as at 41, while the fine material remains suspended in the liquid and passes out therewith over the overflow means 21.

According to my invention the classifier 2 which may be of the type above described or of any other suitable 4,type is provided at y 'its upper end with distributing or splitting means 9 for receiving the coarse material and distributing. it partly to the first or coarse grinding mill 1 and partly'to the second or fine grinding mill 3. Said distributing means 9 may consist of two trough'sor chutes 10 and 11 extending side lby side with a partition 12 between them and flanges or deflectors 13 hinged at the top of said` partition and adapted to be swung to, one side or the other so as to deflect the material into the chute 10 or the chute 11 as the case may be, it being understood that the said chutes are arranged in the path of the material as it is raked off the classier table and forced by gravity therefrom and that said chutes are sufficiently inclined respectively toward the feed means 5 for mill 1 and toward the feed means 14' for mill 3 to cause the coarse material received by the respective chutes to flow to the feed means forthe respective mills.

The operation is as follows:

The material to be ground is supplied by the feed means 5 tothe coarse grinding mill 1 and is therein subjected to grinding action, the ground material passing from `the coarse grinding mill 1 through the delivery means 6 to the classifier 2. In said classifier the ground material is introduced into a body or current of water (Water being supplie-d with the ground material in the required amount), and the operation of the classifier continually' or intermittently rakes the coarser material from such body of water onto an inclined table surface so that it is removed from the water and is eventually discharged over the upper end of the inclined surface of the classifier and falls into the distributing means 9. By suitable adjustment of the deflectors 13 of said distributing means as by tipping some of them to one side and the others to the other side of a vertical position any desired portion of the coarse material delivered thereto can be returned through the delivery means 10 to the feed means 5 for the coarse grinding mill 1. The remainder of such coarse material passes through the delivery means 11 to the feed means 14 for the fine grinding mill 3. By this means I am enabled to maintain each of the mills at full rinding capacity and efficiency. The e ground product from the fine grinding mill passes through launder or delivery means 16 and feeding elevator 17 to classifier 4, the fine portion thereof being delivered b said classifier to the delivery means 7 or example, and the coarser portion thereof being returned to the fine grinding mill 3 by a return connection 15.

My invention is not limited to a system of two mills, but may be applied to systems in which any number of mills are employed in series, classifiers provided with the above described splitting vmeans being connected to receive the product from each mill and to return/a portion of the coarse material to a preceding mill and a portion to the next succeeding mill in the series.

y Wha-t I claimy is:

1. A combination of a coarse grinding mill and a` fine grinding mill, a classifier connected to receive the ground material from the coarse grinding mill and adapted to separate the finer portion of such ground material from the coarser portion thereof, and distributing means for delivering a part of the coarser material so separate to sol lflll the fine grinding mill and returning another portion of such coarse material to the coarse grindingmill.

2. A combination of a coarse grinding mill, a fine grinding mill, a classifier connected to receive the ground material from the coarse grinding mill and to separate the finer-portion thereof from the coarse portion thereof and distributing means adapted to receive the coarser material from the classifier and to return a portion thereof to the coarse grinding mill and to deliver the remainder thereof to the fine grinding mill, said distributing means being adjustable to vary the portion of the coarse material re-4 turned from the classifier to the coarse grinding mill.

3. In apparatus for crushing or grinding material comprising a plurality of grinding mills connected in series and a classifier connected to each grinding mill to receive the product therefrom and adapted to separate the finer portion of such product from the. coarser portion thereof, distributingv means adapted to receive the coarser material from a classifier and to return a portion thereof to a mill preceding such classifier, and to deliver another portion thereof to a succeeding mill.

4. The combination of a plurality of grinding mills, a plurality of classifiers each adapted to receive crushed material from one of said vgrinding mills and to separate the finer and coarser portions of said crushed material, a plurality of delivery means each adapted to receive coarse material from a classifier and toreturn such classifier, and delivery means to recelve a portlon of'the coarse materlal from one of said classliiersv and to deliver the same to a succeedlng mill.

adapted the samef l to the mill from which it was received by In testimony whereof I have hereunto subscribed my name this 21st day of March, 1924.

HENRY KENYON BURCH. l 

